1. Field of the Invention
This invention relates to a method of forming a three-dimensional net-like structure from a material such as a suitable synthetic polymer or a suitable malleable metal. The synthetic polymers include thermoplastic and thermosetting resins and compounds of the resins with or without additives provided they may be formed in a plastic state.
2. Description of the Prior Art
Net-like structures are used for baskets, sacks, cages, and the like. In some cases, they are made from an expanded mesh, wherein slits are cut or stamped form a mesh. Such methods are limited by available sheet stock and have additional production costs of handling the sheets in the storage and cutting rooms, plus the costs of die cutting. The products of such methods are closely related to the paper cutting art of origami but share the inherent problems of low tear strength at the corners of the slits when the pattern is expanded. Furthermore, cutting or stamping out a pattern in a flat disc does not allow one to shape the strands nor to design the strand joints for expansion.
One method of making a net-like structure, such as a basket, from a synthetic polymer material, is to use three-dimensional molds or dies and injection mold or cast the basket. However, three-dimensional molds or dies are very costly to manufacture because they have complex parting planes, and these types of molds or dies have a considerable mass of material which has to be moved backwards and forwards at every forming stroke. Hence the energy requirements for such a process are high. There are also a number of limitations in the depth of the basket and in the shape of the strands and the pattern of strands and strand joints to allow the molds or the dies to part, otherwise the basket cannot be released.